Investigators seek former roommate of missing man

Investigators confirmed today that the bones found Monday in the basement of a Sac City house are those of Mark Koster, who was reported missing three years ago.

The location of the bones in Koster’s former house — which Sac City Police Chief John Thomsen said was “not very accessible” but declined to elaborate — has led law officers to seek the man’s former roommate, whom they have so far been unable to identify.

“We know his first name is Tom,” Thomsen said. “They’d been friends for a long time.”

An autopsy has not revealed how Koster died. Thomsen said that information could take six to eight weeks to get. The State Medical Examiner’s Office used dental records to match the bones to Koster.

The roommate was from another state, possibly Florida or Texas, Thomsen said. He had lived with Koster for about three months before Koster was reported missing.

Anyone with information about the roommate can call the police department at (712) 662-7772.

A Carroll man, Lesly Gehlsen, who bought Koster’s former house at 610 N. Fifth St. in May, found the bones on Monday as he cleaned the basement.

Koster was 58 when his family reported him missing after Koster stopped paying his utility bills, according to court records.

Investigators who searched the house found clothing and other possessions undisturbed — including his pipe and tobacco, the records show. Koster’s vehicle was in the house’s garage.

They found no trace of the man “despite extensive efforts to locate the missing person by the Sac County Sheriff’s Office, the Sac City Police Department, the Division of Criminal Investigation and other law enforcement agencies,” Koster’s brother Daniel Koster wrote to a judge in 2011. A jury later determined that Mark Koster “has suffered death by accidental or other violent means,” court records show, and Gehlsen bought the house.

Thomsen said investigators who searched the house after he was reported missing did not find Koster because they weren’t looking for a tucked-away body.

“It’s nice to get partial closure — he’s been identified,” Thomsen said of the search for Koster. “Now we need to close the other part of how he got where he was.”